Nillable (52°North Shetland 8.2.1 API)

java.lang.Object
- org.n52.shetland.w3c.Nillable<T>

Type Parameters:

T - the instance type
```
public abstract class Nillable<T>
extends Object
```
Represents a tri-state object: can be nil (with an optional message), absent (or null) or present. isNil(), isAbsent() and isPresent() are mutually exclusive true.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`static <T> Nillable<T>`	`absent()` Creates a `Nillable` for a absent instance.
`abstract T`	`get()` Returns the object if present.
`abstract Optional<String>`	`getNilReason()` Returns the optional reason for this object being nil.
`boolean`	`hasReason()` Checks if this `Nillable` is nil and has a reason.
`static <T> Nillable<T>`	`inapplicable()` Creates a new `Nillable`, that is nil because it is inapplicable.
`abstract boolean`	`isAbsent()` Checks if this `Nillable` is `null`.
`abstract boolean`	`isNil()` Checks if this `Nillable` is `nil`.
`boolean`	`isNull()` Checks if this `Nillable` is `null`.
`abstract boolean`	`isPresent()` Checks if this `Nillable` is present.
`boolean`	`isPresentOrNil()` Checks if this this instance is not absent.
`abstract <X> Nillable<X>`	`map(Function<? super T,X> fun)` Transforms this `Nillable` to the target type.
`static <T> Nillable<T>`	`missing()` Creates a new `Nillable`, that is nil because it is missing.
`static <T> Nillable<T>`	`nil()` Creates a new `Nillable` that is `nil`.
`static <T> Nillable<T>`	`nil(String reason)` Creates a new `Nillable` that is `nil` because of optionally supplied reason.
`static <T> Nillable<T>`	`of(T obj)` Creates a new `Nillable` that is either present (if `obj` is not `null`), or absent.
`static <T> Nillable<T>`	`of(T obj, String reason)` Creates a new `Nillable` that is either present (if `obj` is not `null`), nil (if `reason` is not `null`) or absent.
`static <T> Nillable<T>`	`present(T t)` Creates a new `Nillable` from a present instance.
`static <T> Nillable<T>`	`template()` Creates a new `Nillable`, that is nil because it is a template value.
`static <T> Nillable<T>`	`unknown()` Creates a new `Nillable`, that is nil because it is unknown.
`static <T> Nillable<T>`	`withheld()` Creates a new `Nillable`, that is nil because it is withheld.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - isNil
```
public abstract boolean isNil()
```
    Checks if this Nillable is nil.
    
    Returns:
    
    whether or not this instance is nil
    
    See Also:
    
    isPresent(), isAbsent()
  - isPresent
```
public abstract boolean isPresent()
```
    Checks if this Nillable is present.
    
    Returns:
    
    whether or not this instance is present
    
    See Also:
    
    isNil(), isAbsent()
  - isAbsent
```
public abstract boolean isAbsent()
```
    Checks if this Nillable is null.
    
    Returns:
    
    whether or not this instance is null
    
    See Also:
    
    isNil(), isPresent()
  - map
```
public abstract <X> Nillable<X> map(Function<? super T,X> fun)
```
    Transforms this Nillable to the target type.
    
    Type Parameters:
    
    X - the target type
    
    Parameters:
    
    fun - the transformation function
    
    Returns:
    
    the Nillable
  - isNull
```
public boolean isNull()
```
    Checks if this Nillable is null.
    
    Returns:
    
    whether or not this instance is null
    
    See Also:
    
    isAbsent()
  - isPresentOrNil
```
public boolean isPresentOrNil()
```
    Checks if this this instance is not absent.
    
    Returns:
    
    whether this instance is present or nil
  - get
```
public abstract T get()
```
    Returns the object if present.
    
    Returns:
    
    the object
    
    Throws:
    
    UnsupportedOperationException - if this instance is not present
    
    See Also:
    
    isPresent()
  - hasReason
```
public boolean hasReason()
```
    Checks if this Nillable is nil and has a reason.
    
    Returns:
    
    whether this instance has a nil reason or not
  - getNilReason
```
public abstract Optional<String> getNilReason()
```
    Returns the optional reason for this object being nil.
    
    Returns:
    
    the nil reason
    
    Throws:
    
    UnsupportedOperationException - if this instance is not nil
    
    See Also:
    
    isNil()
  - present
```
public static <T> Nillable<T> present(T t)
```
    Creates a new Nillable from a present instance.
    
    Type Parameters:
    
    T - the type
    
    Parameters:
    
    t - the object
    
    Returns:
    
    the present Nillable
    
    Throws:
    
    NullPointerException - if t is null
  - absent
```
public static <T> Nillable<T> absent()
```
    Creates a Nillable for a absent instance.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the absent Nillable
  - nil
```
public static <T> Nillable<T> nil(String reason)
```
    Creates a new Nillable that is nil because of optionally supplied reason.
    
    Type Parameters:
    
    T - the type
    
    Parameters:
    
    reason - the reason (may be null)
    
    Returns:
    
    the nil Nillable
  - nil
```
public static <T> Nillable<T> nil()
```
    Creates a new Nillable that is nil.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the nil Nillable
  - inapplicable
```
public static <T> Nillable<T> inapplicable()
```
    Creates a new Nillable, that is nil because it is inapplicable.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the nil Nillable
  - missing
```
public static <T> Nillable<T> missing()
```
    Creates a new Nillable, that is nil because it is missing.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the nil Nillable
  - template
```
public static <T> Nillable<T> template()
```
    Creates a new Nillable, that is nil because it is a template value.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the nil Nillable
  - unknown
```
public static <T> Nillable<T> unknown()
```
    Creates a new Nillable, that is nil because it is unknown.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the nil Nillable
  - withheld
```
public static <T> Nillable<T> withheld()
```
    Creates a new Nillable, that is nil because it is withheld.
    
    Type Parameters:
    
    T - the type
    
    Returns:
    
    the nil Nillable
  - of
```
public static <T> Nillable<T> of(T obj)
```
    Creates a new Nillable that is either present (if obj is not null), or absent.
    
    Type Parameters:
    
    T - the type
    
    Parameters:
    
    obj - the object (may be null)
    
    Returns:
    
    the Nillable
  - of
```
public static <T> Nillable<T> of(T obj,
                                 String reason)
```
    Creates a new Nillable that is either present (if obj is not null), nil (if reason is not null) or absent.
    
    Type Parameters:
    
    T - the type
    
    Parameters:
    
    obj - the object (may be null)
    
    reason - the nil reason (may be null)
    
    Returns:
    
    the Nillable

Class Nillable<T>

Method Summary

Methods inherited from class java.lang.Object

Method Detail

isNil

isPresent

isAbsent

map

isNull

isPresentOrNil

get

hasReason

getNilReason

present

absent

nil

nil

inapplicable

missing

template

unknown

withheld

of

of